The jaw crusher is a compression type crusher. Feed material is crushed between fixed and movable jaw dies. 

Large particles are crushed in a single layer, referred to as single-layer crushing. Smaller particles are crushed rock on rock, referred to as multi-layer crushing. 

Feed opening (depth of the cavity) defines the maximum feed size of the crusher. 

In the C jaw crusher, the feed opening is measured from the top of the tooth of the fixed jaw to the bottom of the tooth of the movable jaw in a straight line perpendicular to the center line of the crushing cavity. 

The maximum feed size is approximately 80% of the feed opening. 

The open side setting is measured when the crusher is at rest. The setting is measured either top to top, or bottom to top, depending on the tooth profile of the jaw dies. 

The closed side setting can be calculated by deducting the stroke from the OSS. CSS is the most important crusher parameter since it defines the maximum product size and has significant bearing on capacity, product gradation, power draw, and wear. 

Check the Instruction Manual for the permitted minimum CSS.